Diesel fuel, particularly No. 2 fuel oil, has the tendency to gel or "wax" in cold weather. This gelling of diesel fuel is a particularly acute problem in the trucking industry during colder months in portions of the U.S., Canada, Europe and other high latitude environments. During the winter months, temperatures and wind chill factors frequently reach minus 30.degree. Fahrenheit in these areas. In such a temperature and windchill range, diesel fuel tends to gel or wax both in the fuel tank itself and within a fuel line leading from the tank to the engine. In the severest instances of gelling, the diesel engine completely fails. The truck or other vehicle thus must be towed to a service area and the fuel system heated. The towing and down time of the truck results in increased transportation cost. In less severe instances, the gelling can result in loss of power so that the trucks are forced to travel at a slow rate of speed. This also results in increased transportation cost.
Similar cold weather problems exist with the use of hydraulic oil. Typically, hydraulic oils of various grades experience viscosity changes dependent on temperature. In cold weather or winter months, hydraulic oil which is cold provides slower response times to the equipment it is powering. Moreover, cold hydraulic oil may cause: pump damage from cavitation; slower operation from hydraulic motors; high pressure leaks; blown hose ends; blown seals; and other problems. Often it is necessary to warm the hydraulic oil reservoir prior to powered operation of equipment to avoid improper operation.
Problems also exist when diesel fuel or hydraulic oil is warmer than an optimum operating range. In the case of diesel fuel, optimal operating temperatures may range generally between about 60.degree. F. and about 110.degree. F., subject to quality of the diesel fuel, additives therein, and other considerations. Frequently, diesel fuel in trucks and vehicles operating in warmer climates or for long durations produce heating effects within the engines that cause the fuel temperature to exceed the optimum power ranges. This overheating may result in numerous problems, including damage to electronic components in engine systems. Therefore, it is desirable to reduce the amount of heat in the fuel in such situations. Similarly, when hydraulic oil is warmed beyond an optimum range, power control problems and residual heating effects may occur. It is therefore desirable to reduce the amount of heat in hydraulic oil reservoirs when the temperature of such reservoirs exceeds a predetermined range, but at the same time be able to provide rapid heat rise to such fluids as warranted.
Numerous methods and apparatus have been used in the past in an attempt to solve these or related problems. In many of these prior systems, disadvantages exist. For example, most systems do not provide temperature sensing means which are placed directly into a fuel or oil reservoir tank bottom (let alone in an even more advantageous position) and therefore do not accurately sense a temperature of fuel or oil therein. Further, many prior art systems provide means for bypassing flow of fuel in response to various pressure/temperature sensing means rather than improved regulation of the flow of a heat exchange medium. Moreover, prior art systems do not typically permit continuous flow heat exchange loops during all phases of operation of a vehicle, truck, or other equipment in which the system is functioning. A continuous flow loop during all phases of operation is particularly desirable in cooperation with preheating or precooling devices, as well as pumping means.
Frequently, fuel and oil heating devices do not adequately safeguard electronic components which are now more prevalent within the control systems of engines. This in itself creates various problems. Overheating of electronic components in engine control systems often results in failure of those components. A secondary effect of failure of engine control components may be substantial damage to the engine, or at least a significant degradation in engine operation.
Other disadvantages of present day power fluid temperature control devices include: electrical components which may cause significant installation and maintenance problems; valves which must be manually operated to effect bypass conditions; inefficient placement of heat exchange conduits in relation to the diesel fuel and/or hydraulic oil; difficulty in installation; and, numerous components requiring substantial supply and repair concerns. Other present day systems do not provide devices which may be configured for either heating or cooling purposes using virtually interchangeable parts, while other systems are not optimally located on the top portions of diesel fuel and/or hydraulic oil reservoirs, or at the fuel sending gauge sites. In such systems, adaptability to operation in various climates is also often impractical.
What has been needed has been an improved system for mechanically bypassing heat exchange medium flow; providing an easily installed and readily adaptable system for warm weather or cold weather operations; providing means for temperature sensing of diesel fuel or hydraulic oil at a location just prior to the fluid entering the critical components of the operating system but (optionally) after preheating has occurred in both the reservoir and the intake conduit for such fluid; providing for continuous loop heat exchange medium flow when the system is in a bypassed mode; providing improved heat rise for warming of power fluids; providing means for warming or cooling fuel oil when that oil is being drawn into a fuel line from a diesel fuel reservoir; and, providing a non-electrical, completely mechanical actuator means for operating the manifold device, thereby permitting more reliable operation. Also, a power fluid reservoir and intake conduit heating and cooling system which is relatively inexpensive to manufacture and which is easily installed is preferred.
Objects and advantages of the present invention in achieving these and other goals will become apparent from the following descriptions, taken in connection with the accompanying drawings, wherein are set forth by way of illustration and example certain embodiments of the present invention.